nteract/papermill

Python parameter with `None | ` union type is logged as unknown

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#806 opened on Sep 5, 2024

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bughelp wanted

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Description

🐛 Bug

# template.ipynb parameters block
foo: None|str = None

$ papermill -p foo BAR ...
Passed unknown parameter: foo

Expected: this warning not to show up, foo should be recognized as a valid parameter.

Also note:

  • Despite the warning, the above example still properly injects the parameter value
  • Optional[str] does not suffer from this issue, just type union style
  • str|None (change the type order) produces the same warning log

papermill version == 2.6.0

Contributor guide

Research direction
Look at the parameter parsing logic in papermill, likely in `papermill/parameter.py` or `papermill/iorw.py`. The bug is that `None | str` is not recognized as a valid type hint, while `Optional[str]` works. You'll need to modify the type detection to handle PEP 604 union syntax. Check how `typing.get type hints` or custom parsing is used, and ensure that `None | X` is treated as equivalent to `Optional[X]`.
Tech stack
python
Domain
cli
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Basic PythonUnderstanding of type hintsPapermill usage
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
85